Diffusion/filtration devices are used for different kinds of medical treatment, such as hemodialysis, hemofiltration, plasmapheresis and immunotherapy. Other fields of use for such devices are for instance dialysis in general and filtration in general, for example in connection with cleaning or desalination of sea water.
In connection with the production of devices of the above kind, each end of a housing with a bundle of fibers placed therein is normally enclosed in a casting mold into which the material for the adjacent end wall is fed in a liquid condition, thereby penetrating into and around the fibers. This penetration is controlled by the casting in a manner such that the penetration into the fibers is less than that around the fibers, making it possible to open the ends of the fibers by making a transverse cut between the surfaces defined by the two different penetration depths.
The manner in which the end walls may be molded is described in more detail, for example, in EP-B-0 165 478, and U.S. Pat. Nos. 4,227,295 and 4,329,229, as well as in copending U.S. patent application Ser. No. 237,504.
Before molding the end walls, the inside of the fibers, as well as the outside of the fibers, are normally flushed by a cleaning liquid. This flushing is normally performed in a separate housing having the simple form of an open-ended tube. If, instead, it should be performed in the final housing of the diffusion/filtration device, there is the risk that a portion of the cleaning liquid may remain in the housing, especially in inlets and outlets arranged in the housing wall.